摘要:
A method for assessing NO2 generation efficiency in a diesel engine after-treatment (AT) system having a diesel oxidation catalyst (DOC) downstream of the engine generating the NO2 and a selective catalytic reduction (SCR) catalyst downstream of the DOC converting NOX with the aid of the NO2. Engine exhaust gas flow is passed into the AT system and a reductant is injected into the gas flow between the DOC and the SCR catalyst. SCR inlet gas flow temperature is monitored during transient engine operation and DOC inlet and SCR catalyst outlet NOX concentrations are detected when the SCR catalyst inlet gas flow temperature is in a predetermined range. SCR catalyst NOX conversion efficiency is determined using the detected DOC inlet and SCR catalyst outlet concentrations of NOX. Additionally, whether the NO2 generation efficiency is at or above threshold efficiency is assessed by comparing the determined and threshold NOX conversion efficiencies.
摘要:
A method and apparatus for controlling a diagnostic module for an exhaust gas sensor in a vehicle is provided. The exhaust gas sensor is located in an exhaust pathway in the vehicle. The diagnostic module may be configured to perform a signal range verification of an oxygen sensor portion of the exhaust gas sensor. A controller is operatively connected to the exhaust gas sensor and to the vehicle engine. The controller disables the diagnostic module when one or more entry conditions are satisfied. The entry conditions may include requiring the engine speed to be greater than a fuel cut-off threshold, the fuel cut-off threshold being the engine speed at which the fuel to the engine is terminated. The entry conditions may include: no fuel being delivered to the engine; and a vehicle exhaust brake mode being activated such that the exhaust pathway from the engine is obstructed.
摘要:
An exhaust treatment system is disclosed that can diagnose the performance of an exhaust treatment oxidation catalyst in converting NO to NO2. The exhaust treatment system is fluidly coupled to an internal combustion engine, and includes an oxidation catalyst disposed in an engine exhaust stream; a reductant source for injecting a reductant into the exhaust stream downstream of the oxidation catalyst; an SCR catalyst disposed in the exhaust stream downstream of the reductant source; and a gas sensor, disposed in the exhaust stream downstream of the oxidation catalyst and upstream of the reductant source, comprising a plurality of sensing or pumping cells that measures NO concentration in the exhaust gas and NO2 concentration in the exhaust gas.
摘要:
An exhaust diagnostic control system comprises a test enabling module, an exhaust gas temperature management module in communication with the test enabling module, and a component management module configured for executing a test for determining a reduction efficiency associated with the after-treatment component. The test enabling module is configured for assessing a reliability of an estimated level of reductant load on an after-treatment component, and, based on the reliability, selectively facilitating disablement of a subsequent test for determining an efficiency of NOx reduction in the after-treatment component. The exhaust gas temperature management module is configured for selectively adjusting a temperature of the after-treatment component to a predetermined temperature range using intrusive exhaust gas temperature management. The test for determining reduction efficiency comprises determining a NOx reduction efficiency of the after-treatment component.
摘要:
An apparatus and method of controlling a vehicle aftertreatment system is provided. The aftertreatment system treats exhaust gas produced by the vehicle engine and includes a particulate filter, and a NOx reducing device such as a selective catalytic reduction (SCR) device. The particulate filter is configured to regenerate to remove accumulated particles when the exhaust gas is heated above a regeneration temperature. A diagnostic device is included for monitoring the aftertreatment system. The diagnostic device may be a sensor for measuring the oxides of nitrogen (NOx) and/or an SCR efficiency monitor. A controller is employed to optimize the function of the diagnostic device. The controller does not enable the diagnostic device when the vehicle is powered until one or more entry conditions are satisfied.
摘要:
A method of monitoring regeneration of a particulate filter is provided. The method includes evaluating whether a regeneration event is based on a fixed threshold condition; selectively setting a pass or fail status based on the evaluating; and generating a message indicating the pass or fail status.
摘要:
A vehicle includes an engine, an exhaust system having a particulate filter which removes soot from the exhaust stream, a sensor, and a controller. The sensor measures instantaneous differential pressure across the filter. The controller executes a method to selectively enable or disable execution of an efficiency diagnostic of the filter as a function of a learned differential pressure offset value. The controller may also compare the differential pressure to a calibrated threshold and execute a control action when the differential pressure falls within an allowable range of the threshold. This may include applying the differential pressure offset value and enabling execution of the diagnostic using measurements from the zeroed sensor. Another control action may be executed when the measured differential pressure is not within the allowable range of the threshold, including disabling the execution of the diagnostic and setting a diagnostic code indicating that the sensor may be faulty.
摘要:
A method of assessing overall efficiency of a selective-catalytic-reduction catalyst includes monitoring instantaneous efficiency of the catalyst. The method also includes determining the overall efficiency by summing instantaneous efficiency values weighted by a first set of coefficients if the most recent instantaneous efficiency value is above an instantaneous efficiency threshold. The method additionally includes determining the overall efficiency by summing instantaneous efficiency values weighted by a second set of coefficients if the most recent instantaneous efficiency value is equal to or below the instantaneous efficiency threshold. Furthermore, the method includes determining whether the overall efficiency has dropped below an overall efficiency threshold and reporting when the overall efficiency has dropped below the overall efficiency threshold. The second set of coefficients weighs the most recent instantaneous efficiency value more heavily than preceding instantaneous efficiency values as compared with the first set of coefficients. A system and a vehicle are also disclosed.
摘要:
A method and apparatus for controlling a diagnostic module for an exhaust gas sensor in a vehicle is provided. The exhaust gas sensor is located in an exhaust pathway in the vehicle. The diagnostic module may be configured to perform a signal range verification of an oxygen sensor portion of the exhaust gas sensor. A controller is operatively connected to the exhaust gas sensor and to the vehicle engine. The controller disables the diagnostic module when one or more entry conditions are satisfied. The entry conditions may include requiring the engine speed to be greater than a fuel cut-off threshold, the fuel cut-off threshold being the engine speed at which the fuel to the engine is terminated. The entry conditions may include: no fuel being delivered to the engine; and a vehicle exhaust brake mode being activated such that the exhaust pathway from the engine is obstructed.
摘要:
An internal combustion engine includes a particulate filter that is configured to treat exhaust gas. A method for monitoring the particulate filter includes employing a soot sensor to monitor the exhaust gas downstream of the particulate filter. A fault is detected in the particulate filter when accumulated soot mass indicated by the soot sensor exceeds a soot mass threshold over a course of engine operation between a first regeneration event and a second regeneration event of the particulate filter. A control module associated with operation of the internal combustion engine is notified of the fault.